Painful Birth

6/17/22, 11:05 PM The painful birth of TI99/4 The Wayback Machine - https://web.archive.org/web/20001120204300/http://perso.club-internet.fr:80/pytheas/english/TI99_history.html The painful birth of TI99/4 The purpose of this page is to explain the technical choices which were made when designing TI99/4. Incidentally, I tell about a few little-known facts. Information in this page is not guaranteed 100% correct, althought I hope it is. Also, you should understand I am just the compiler and popularizer of information I found elsewhere. Sources : Article by Dan Eicher "The TMS9985", 12/06/1996 (TI Hardware Manual). Article by Herbert H. Taylor "TI-99/4 - THE EARLY DAYS", 11/25/1994 (TI Hardware Manual). "TI GPL USER'S GUIDE", 12/2/1979. Quick historic notes TI99 models : TI99/4 The original TI99. Released in 1979 (first prototypes in 1978). Was intended to use a TMS9985 microprocessor (or was it a microcontroller ?), but eventually used a 3MHz TMS9900 processor. Features 256 bytes of CPU RAM and 16kb of video RAM. TI99/7 Never released, developped parallelly with TI99/4, some prototypes built in 1980. Compared with TI99/4, features 64.25kb of CPU RAM, a memory pager, and a better keyboard. It included a speech synthesizer, P-Card, one disk unit, a serial interface, a modem, and an expansion port, all in a single box. Its design seems to prefigure both TI99/8 and TI Business Systems. TI99/4A An improved TI99/4. Released in 1981. Features an additional graphics mode, better keyboard, and revised, smaller CPU ROMs. TI99/8 https://web.archive.org/web/20001120204300/http://perso.club-internet.fr/pytheas/english/TI99_history.html 1/7 6/17/22, 11:05 PM The painful birth of TI99/4 Never released, some prototypes built in 1983. Features a 10MHz TMS9995 microprocessor, a memory pager, 64.25kb of CPU RAM, improved ROMs, and built-in TI-extended basic, speech synthesizer and P-Card. TI99/2 Never released, some prototypes built in 1983. Features a 10.7MHz TMS9995 microprocessor, 4.25kb of CPU RAM, and built-in TI-extended basic. To reduce costs, video was simplified, and sound absent. In spite of its name, this computer is not really compatible with TI99/4(A). TI99/4B & TI99/5 Never released. I only know the name of these machines, even their existence remains uncertain. I guess both names match the same machine, and that it was a TI99/4A with a TMS9995 processor instead of the old TMS9900. TI99 was abandonned in 1983. Why TI99 is (almost) 8-bit TI99/4(A) has frustrating…